Method of and apparatus for electric-resistance welding



March 27, I928- 1,664,630

4. H. GRAVELL KETHOD OF AND APPARATUS ELECTRIC RESISTANCE WELDING Filed ll arch 2a 1926 gwuentoz James/56mg 67am]! Patented Mar. 27, 1928. I

UNITED STATES PATENT OFFICE.

mn'rnon or AND APPARATUS m1. nn-nc'rmc-nnsrs'mncn WELDING.

Application filed March 23, 1926. Serial No. 96,684.

This invention relates to that type of welding wherein the heat thereof is developed directly in the work to be welded by the resistance of the work to the passage of an electric current.

The ilivention is especially useful for electric resistance welding by methods and apparatus in which pointed electrodes, buttons, rollers, etc. are employed for loealizing the welding.

Heretofore difliculties have been encountered in heavy duty spot welding and seam welding and in all forms of welding where large volumes of current have been localized by means of electrodes. Also in the case of large work difliculty has been encountered from the fact that in previous methods the work circuit or current has necessarily encircled the work in order that it may be applied at the desired point of welding and therefore the work current circuit has been subjected in many cases to a prohibitive amount of self-induction from the work.-

overcome the latter difiicultylby reducing the amount of current flowing through any one electrode without reducing the volume of current flowing through the part to be welded; to reduce the counter-electromotive force generated in the welding current or'circuit by the work, to simplify the heating circuit so that the throat ofthe welding apparatus is eliminated; to provide a'throatless apparatus, thus allowing any size work to be weld.-

ed on the same machine, to extend the limitations of welding, to produce better and stronger welds, and to facilitate welding so that many structural shapes and heavy parts may be brought within the category of weldable products, and to attain other advantages which will be apparent to those skilled in the art.

Generally stated, the invention consists in passing the parts to be welded between opposite poles of two independent welding cir cuits, said poles or electrodes constituting the welding vise or pressure device and arranged more or less closely 1n direct line with one another to properly apply the pressure, said working circuits or currents cooperating to heat the work in such manner that the current of one circuitonly passes through one of said pressure electrodes and the current of the other through the other electrode while the current of both passes over the work itself or the elements thereof and in a line coinciding with the line of pressure. f y

The invent-ionconsists-further in the details of the process and apparatus as heremore particularly described and indicates the point of application of the currents and of the welding to be effected in an overlapped portion of two plates or work members L L. D indicates a platen contact electrode or terminal for one welding or work currentand 'E a similar contact electrode for the other welding current or circuit. Said electrodes D and E are a plied respectively to theelements L L. indicates anvils or rests designed to support the work against pressure a plied on the con.- tacting electrodes D for t e pur ose of making good electrical contact wit .the work. Suit-able transformers for the two welding currents are indicated at F G respectively while a suitable switch J controls the applisame volume of current is present at all cation of the welding current. points in the circuit.

Referring now to Fig; 1, it is evident that the current flowing from one welding elec 6 trode A although passing the joint to be welded B does not enter the opposite welding terminal C but completes 'the circuit by means of the platen contact electrode l) and what is true of circuit A, B, .D

10 is also true of the circuit E, B, G. Although itself to get across the joint to be welded,

these circuits coalesce at the 'joint 13 to be and although these same means may be apwelded they do not cross each independent plied as adjuncts to myprocess, it is evicircuit remaining intact' and returning to dent from the above description that I conthe point of originwhich is-the transformcentrate my currents in one'by shaping the 15 or F and the transformer G respectively. electrodes, providing buttons orspotting As commercially carried out the electrodes the work, but also by causing two independ: :A and G constitute the jaws, of a welding entcurrents to coalesce at the spot to be vise between which the. parts to be welded welded, thus employing two means simulare placed. The contacting electrodes D. taneously by causing my welding currents and E may be made .to cover a relatively to be concentrated r F large area, so that practically no heating It is well known that two parallel curefiect is produced where they contact with rents attract each other hence it will be seen the work. Also the contact electrodes D and that in my case the two independent cur E being opposed by anvils H and I may ex rents will tend to .concentrate in the work at considerable ressure on the metal of between the two welding electrodes Therethe work. In ot er words, a contact elec-ccentrate thecurrent for welding, especially spot welding, solely by means of the elecsuch as the introductionof buttonsbetween the electrodes and the work or by so shaping to the work. t be greatly diminished.

The primary circuits actuated and the What I claim as my'invention is:

welding transformers F and G maybe con- 1. The method of heating by causing a 1 nected in parallel'or series, provided hownumber of independent electric currents to ever the polarities of the heating terminals coalesce or pass in the same line or path are such that the two welding currents do through the spot or section of work to be not oppose each other. In Fi 1 the transheated by causing one of said currents to.

formers are connected in para pass through one only of a-pair of eleccl and operated by a switch shown at J.

trodes themselves or by variations of this idea- 'the'work that the current must'concent-rate' The practice has been heretofore to con 7 fore by my invention the losses of heating trode and a platen may constitute an auxilcurrent due to circulation of current across iary vise for holding the contact electrode the work outside of the line of pressure will I v trodes engaged with the work in line with o In Fig. 2 isshown an apparatus applying said spot or section but at opposite sides the invention to the production of seani thereofand the'other current to pass :simi- 40 welding "where the electrodes and anvils larly through the other electrode while the take the form of rolls. current of both conducted through the .It is evident from that two independent welding circuits are said work engaging electrodes. provided, said circuits located respectively the above description work to the point of heat independently of 2. The method of spot welding consisting I 415 wholly on opposite sides of the work, thus in concentrating the current by means of a eliminating t e necesslty for the so-called pair of electrodes and by causing a. plurality welding throat. As will beseen, the presof independent currentsto coalesce and pass sure electrodes are electrodes of two indein the same'line .throughthe point to be pendent work circuits but constitute towelded said line coinciding with the line of 50 gether a welding vise for welding being in promo-exerted by. said electrodes, each substantially line with one another or said current posing through one electrode in the line of welding presure, but the heat and through the work' independently of the 7 -ing current does not pass'fromondwelding other electrode and exerting pressure by electrode to the other through the joint or means of the electrodes '-to complete the 55 portion of work operated upon. It is also weld evident that'asboth circuits pass through 3.

at thispoint is-four times as great as any op other. point in either circuit, due to'the fact cults carrying currents flowing independlll that'there is twice as much current passing ently of one another but coalescing in the through the point to be welded as at any heated section of work-sin the same point or otherpoint in either circuit; thus the same -line coinciding with the line of pressure exheating efiectis produced with one-fourth erted by said jaws and said electrodes the amount of current as would be required being electrically connected respectively as should the circuit a simple one where the throughthe independent sources 0 current P v p 7 M An apparatus for'welding consisting the point to be welded the heating cited in a welding vise, the'jawsmf which are d electrodes :of two independent cirwith work engaging contact blocks for completillg each circuit through the work inde pendently of a welding jaw.

4; An apparatus for welding consisting of two independent circuits each supplied with work current and three work engaging contact Vises in a row, the jaws of the central vise constituting respectively opposite electrodes of the two independent circuits, while the end vices constitute respectively terminals of said circuits of opposite polarity to that of each jaw of the central vise, the currents of said circuits being passed simultaneously through the part of the work to be heated.

5. In an electric resistance welding apparatus, two work current circuits engaging respectively by opposite poles with opposite sides of the work in the line of welding pressure, said electric circuits each having a remaining pole engaging with the element of the work opposite that engaged by its first-named pole but outside the zone of heating, the heating at the point of electric resistance taking place by the combined effect of the currents in two independent circuits each comprising one heating electrode only, while the current at the point of contact of each electrode in the line of welding pressure on the Work is that of one circuit only. Y

6. The herein described method of electric resistance welding by the application of two work currents or circuits consisting in including the work between two pressure electrodes in line with one another and forming respectively opposite poles of two work current circuits, completing each circuit through two other electrodes forming respectively remaining poles of said circuit and applied to one side of the line of welding pressure, the points of engagement for the two electrodes of each circuit being on the same side of the work, and each said pressure electrode carrying the current of one source of work current only.

7. The method of electric resistance welding by combining-in the independent work two Work current circuits each located entirely to one side ofthe work and passing thecur'rents into the work each by .a pressure electrode and by an electrode to one side thereof conducting the current into the same side of the work for return to the place of heating directly through an unheated section of the work independently of any pressure electrode.

8. The process of electric spot welding consisting in gripping the parts to be welded between a positive electrode of one electric circuit and a negative electrode of another electric circuit, each said circuit carrying a current independently of the other, and passing the two currents of said circuits uncrossed through the surfaces to be welded in the same line coinciding with the line of pressure of the said electrodes so that the currents of said independent sources will coalesce in said line to heat the same= and adjlulst the gripping pressure to complete the we c. 4

9. In an electric heating apparatus, means for heating, the work by two work current sources flowing in independent circuits through two work engaging heating electrodes, one only for each circuit, pressing on the'work in direct line with one another and consisting respectively of poles of said circuits of opposite polarity and means for each circuit independent of the other for conducting the current of each circuit into the work at a. point remote from the place of heating, the circuit being completed therefrom to the point of heating independently of a work engaging contact.

10. The method of electric welding con sisting in causing two parallel currents from independent sources to coalesce in the same line of pressure at the point to be welded between two opposing pressure devices formmg respectively opposite poles of said sources and each circuit including one only of said pressure devices.

11. The method of welding two pieces of metal together consisting in interposing the same between two electrodes forming respectively opposite poles of two independent work circuits and completing each work current circuit byengaging it with the side of the-work engaged by the electrode of the other circuit but at a point thereof to one side of the place of welding for completing the circuit of each current by flow'through.

the work to the point of heating'independently of a work engaging contact.

12. The herein described improvement in electric welding consisting in passing the currents of separate heating circuits through the section of work to be welded in the same line with the line of pressure of two electrodes engaging the work at opposite sides thereof, each through one of said pressure electrodes and directly to the point or section -to be heated through the work on the same side with the opposite electrode and independently thereof.

13. The herein described improvement in electrically welding two plates or pieces of metal together by heat developed at a place of contact between them consisting in supplying the work current from two separate heating sources passing through the work in the same line, said sources supplying their currents to the point of heating independently of one another each by an electrode applying pressure in the line of heating and through a portion of work engaged by an opposite electrode and conducted to the point of heating through said work independently of said opposite electrode.

14. The method of electric heating concarrying the current of one circuit onl and sisting in pinching the section or point. of having its' circuitv completed throng the' work to be heated between two pressure elecwork to the place of heating independently trodes in line with one another and forming of the other electrode. respectively opposite electrodes of two sepa- Signed at New York in the county of New rate or independent work current circuits York and State of New York this 22nd daywhose currents are passed through the work of March, A. D. 1926.

in the same line or path, each said elect-rode JAWS HARVEY GRAVELL.

CERTIFICATE or coRREcrIoN. Q

atcnt No. l,6 64 03 Q. Granted Mhrch27, 1928, to

JAMES HARVEY cmvrui.

.lt lshcreby certificd that error appears in the prilitefl s above numbered patent i'equiring correction as follower Pa srrlke out l:he'word "independent" and imzert the-same before the word "work" lane 49; and that the'said Letters Paten't should he read with this correction m herein that the same may conform to the Y Y t record. of ti; o v

Signed and ,SealQd this 13? day of May, A. 'D. 1928f 935* o ge 3;. line 48,- claim I,

pecificaticn of the 1 -Acting Commissioner-of Patents.

CERTIFICATE 0F CORRECTIQN.

Patent No, 1,664,030. Granted March 27. 1928, to

JAMES HARVEY GRAVELL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as ioiiows: Page 3, iine 48, claim 7, strike out the word "independent" 352d insert the same before the word "Work" in line 49; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 1st day of May, A D. 1928.

M. J. Moore,

(Seal) Acting Commissioner of Patents. 

